Unmanned aerial vehicles (UAVs) are gaining interest in diverse applications to assist in everyday activities and operations. Above ground, UAVs are in some cases a more efficient, less expensive, and safer alternative to manned aircrafts currently used for photography, inspection and security. For example, by attaching camera, infrared, and/or LiDAR payloads, UAVs can provide a low-cost method of obtaining highly accurate 3D data and aerial photography. For example, UAVs are now commonly used in open pit mining operations for applications that include stockpile surveying, 3D pit modelling, facilities management, accident reporting, progress monitoring, and environmental assessment [8]. In mining, UAVs may add value to daily operations, in applications such as pre- and post-blast monitoring in order to identify the presence of misfires and wall damage and to reconcile the blast results with expected results; a UAV equipped with a magnetometer may be used for mineral exploration surveys; and UAV surveys may be used for solids modelling at tailings dams and stability monitoring [8].
In mining applications, UAVs have so far been mostly limited to surface applications. Harsh underground environments pose many obstacles for flying UAVs. The confined space, dampness, reduced visibility, air movement, and lack of control signal propagation hinders most operators from being able to fly a drone underground. It may be that truly practical uses for UAVs underground will require either autonomous or semi-autonomous flight capabilities. Although there are many difficulties with flying underground, the potential benefits from a working system could greatly improve mining and surveying operations. The potential benefits of deploying UAV platforms underground include access to unreachable and dangerous locations and aid in rescue operations. These benefits have the potential to greatly improve mine monitoring and mine safety. Research has shown that current UAV technologies exist that allow for autonomous indoor flight. Extensive research has been done to develop UAV systems that are capable of performing on-board simultaneous localization and mapping (SLAM), which can allow them to navigate and map a foreign environment autonomously [1, 5]. Grzonka [5] successfully used an open hardware quadrotor to autonomously navigate and map an office building. The research outlines the localization, mapping, path planning, height estimation and control of the autonomous quadrotor. Other research has been done that exploits autonomous UAVs for search and rescue. Kassecker [7] proposed a software and hardware framework for a quadrotor capable of indoor and outdoor urban search and rescue and Rudol [11] developed a system for human body detection and geolocalization using an autonomous UAV. The use of autonomous UAVs in search and rescue has the potential to improve situational awareness and surveillance for a rescue team.
A significant problem with implementing these methods in underground mines is that current UAV hardware may not be capable of withstanding harsh underground environments, line-of-sight visibility and direct communications are highly limited, and there are additional underground constraints that may pose additional challenges.